1. Field of the Invention
The present invention relates to a heat-dissipating device, and in particular to a heat-dissipating device for supplying cold airflow.
2. Description of Prior Art
In general, the interior of a computer host is equipped with various electronic elements or devices (such as a central processing unit, a power supply, a hard disk driver or the like) that generate a great amount of heat in operation. Further, a sealed casing is mounted outside the computer host to protect the computer host but unfortunately affect the heat dissipation of the computer host, which causes the accumulation of heat in the computer host together with an elevated temperature. A common solution is to install a heat-dissipating device on the computer host to reduce the inside temperature, thereby protecting the electronic elements and devices in the computer host from suffering damage to affect their normal operation.
A conventional heat-dissipating solution is to install a heat-dissipating fan on a rear surface of the computer host. External air is introduced into the computer host by the heat-dissipating fan to reduce the temperature in the computer host. However, since the weather in Taiwan is warm throughout the year, the temperature of external air is usually in the range of 25 to 35° C. Thus, the above heat-dissipating fan merely blows warm air into the computer host rather than cold air. Therefore, the heat-dissipating effect of the heat-dissipating fan is limited.
With the development of thermoelectric cooling chips, many manufacturers propose a novel heat-dissipating device for the computer host, in which a thermoelectric cooling chip is combined with a fan. After the thermoelectric cooling chip is supplied with electricity, one surface of the thermoelectric cooling chip is heated up and this surface is referred to as a “hot-end surface”. The other surface of the thermoelectric cooling chip is cooled down and this surface is referred to as a “cold-end surface”. When external air is introduced into the heat-dissipating device by the fan and brought into contact with the cold-end surface, the temperature of the external air will be reduced to form a cold airflow. Then, the cold airflow is introduced into the computer host to lower the temperature of the electronic elements therein.
In practice, after the thermoelectric cooling chip is supplied with electricity, the temperature of the cold-end surface will be lower than 0° C., thereby generating a strong cooling effect. However, if the external air does not exchange heat with the thermoelectric cooling chip to form a cold airflow, frost will be generated on the cold-end surface. As a result, when a user turns off the computer host or de-energizes the thermoelectric cooling chip, the frost on the cold-end surface will be melted to become condensed droplets, which will rust the electronic elements in the computer host and even generate a short circuit.
Further, the conventional heat-dissipating device utilizing the thermoelectric cooling chip still has problems as follows. Some manufacturers utilize a finned cooler to be brought into contact with the cold-end surface, thereby increasing the contact area between the external air and the cold-end surface. However, the actual contact area between the finned cooler and the cold-end surface still remains the area of the cold-end surface. Thus, the cold generated by the cold-end surface cannot be conducted to other places rapidly and uniformly to be heat-exchanged with the external air. Thus, frost will still be generated around the contacting portion between the cold-end surface and the finned cooler. As a result, the frost will be melted to form condensed droplets, and the problems of rust and short circuit still exist.
On the other hand, since the contact area between the fined cooler and the cold-end surface is limited, the heat-exchanging distance between the external air and the finned cooler is also restricted. As a result, the external air cannot be heat-exchanged sufficiently with the cold-end surface, and thus the cold generated by the cold-end surface cannot be distributed uniformly in the external air. In other words, the air close to the cold-end surface is cooler but the air away from the cold-end surface is warmer. Such a temperature gradient becomes larger especially when the travelling distance of the cold airflow is longer in the heat-dissipating device.
In view of the above problems, the present Inventor proposes a novel and reasonable structure based on his expert experience and deliberate researches.